In drilling a wellbore in a subterranean formation, such as for the recovery of hydrocarbons, a drill bit is connected to the lower end of a drill string that includes a plurality of drill pipe sections connected end-to-end. The drill bit is rotated by rotating the drill string at the surface and/or by actuation of downhole motors or turbines. With weight applied to the bit from the drill string, the rotating drill bit engages the formation causing the drill bit to cut through the subterranean formation by either abrasion, fracturing, or shearing action, thereby forming the wellbore.
Several types of drill bits are used in drilling operations, and may include percussion hammer bits, roller cone bits, fixed cutter bits, and drag bits. In drilling operations using percussion hammer bits, the drill bit is mounted to the lower end of the drill string, and the drill string moves the drill bit back and forth axially to impact the formation to crush, break, and loosen formation material. To facilitate such effect, multiple inserts or cutting elements may be disposed on a face of the drill bit to impact the formation and crush, break, and loosen the formation material. In order to promote efficient penetration, the percussion hammer drill bit is “indexed” so that the cutting elements contact fresh formations for each subsequent impact. Indexing is achieved by rotating the percussion hammer drill bit a slight amount between each axial impact of the bit with the formation. In such operations, the mechanism for penetrating the formation is of an impacting nature, rather than shearing nature. The impacting and rotating percussion hammer drill bit engages the formation and proceeds to form the wellbore along a predetermined path toward a target zone.